Michelle Miller is a chronic sleepwalker. She and her husband Dan Miller are trying to have their first child after she had a miscarriage the year before. One night she sleepwalks into the bedroom of her neighbor Luke Williams while his wife Nancy is out of town. They have sex; she is unaware of this but he not only knows about it but falls madly in love with Michelle and decides he wants to leave Nancy for her. Michelle gets pregnant, but doesn't know whether the baby is Dan's or Luke's.
Greg Heffley is headed for big things, but first he has to survive the scariest, most humiliating experience of any kid’s life – middle school! That won’t be easy, considering he’s surrounded by hairy-freckled morons, wedgie-loving bullies and a moldy slice of cheese with nuclear cooties!